Abstract

The information on the Late Palaeozoic deposits of the New Siberian Islands is essential to clarify the palaeogeography of the surrounding Arctic Region and to quest the original location of the New Siberian continental block prior to the Amerasian ocean opening. The best Upper Palaeozoic section of the islands, located in the western part of the Kotel’ny Island (Tas-Ary Peninsula), was examined in detail. The studied rocks characterize a transitional facial zone between the northeastern shallow-water (central areas of the Kotel’ny Island) and the southwestern deep-water ones (Bel’kov Island). The stratigraphy of the Carboniferous and partly Permian strata was specified by the study of four fauna groups, detrital zircon dating, and structure interpretation. The section demonstrates a gradual change of depositional environments from shallow-marine in the Lower Carboniferous to deep-water in the middle Carboniferous and Permian. The Tournaisian and Visean rocks (Tas-Ary Formation, not less than 950 m) were formed on the open shelf or ramp with predominant carbonate sedimentation. They were deposited above the storm-wave base during the early Tournaisian and at greater depth later. The Serpukhovian–Middle (?) Permian rocks (Bel’kov Formation, not less than 300 m) were accumulated on the deep-water subaqueous slope and, possibly, at its base. Black shales and turbidite sandstones compose a significant part of the Bel’kov Formation. Sandstones have a siliciclastic–carbonate composition in the upper Lower Carboniferous and are carbonate-free up the section. The boundary between Tas-Ary and Bel’kov formations corresponds to a change in the shelf-to-basin profile and depositional style. At this time (the beginning of the Serpukhovian), the subsidence rate increased, a pronounced slope was formed, and a new source of clastics appeared on land. This reorganization was probably related to the Northern Taimyr orogen rise. The lithological similarity of the Lower Carboniferous deposits of the Tas-Ary Peninsula and Southern Taimyr, the synchronous shift in sedimentation from carbonate to terrigenous rocks, and the same source of clastic material for the Upper Carboniferous–Permian sandstones in both regions indicate their belonging to the same sedimentary basin in the Late Palaeozoic. We believe that the western part of the New Siberian Islands represented a continental margin in Late Devonian, Carboniferous and Permian times, and that it was a continuation of the Verkhoyansk margin. The latter is possible, taking into account rotation of the New Siberian Islands block according to the two-pole rotational model of the Amerasian basin opening.

中文翻译：

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新西伯利亚群岛（塔斯阿里半岛，科特尔尼岛）上古生界的关键部分

摘要

有关新西伯利亚群岛晚古生代沉积物的信息对于阐明周围北极地区的古地理以及在Amerasian海洋开放之前寻求新西伯利亚大陆块的原始位置至关重要。对位于科特尔尼岛（塔斯艾里半岛）西部的岛屿上最好的上古生界进行了详细检查。研究的岩石具有东北浅水区（科特尔尼岛的中部地区）和西南深水区（别尔科夫岛）之间的过渡面部区域的特征。石炭纪和部分二叠纪地层的地层学是通过研究四个动物群，碎屑锆石定年和构造解释来确定的。该部分说明了沉积环境从石炭纪下层的浅海到中石炭纪和二叠纪的深水的逐渐变化。图尔尼斯和Visean岩石（Tas-Ary地层，不少于950 m）形成在开放的陆架或斜坡上，主要是碳酸盐沉积。它们在早期的图奈人时期沉积在风暴波基之上，并在以后更深处沉积。Serpukhovian-Middle（？）二叠纪岩石（Bel'kov组，不少于300 m）聚集在深水水下斜坡上，并可能在其底部。黑色页岩和浊浊砂岩构成了贝尔科夫组的重要组成部分。下石炭统上部的砂岩具有硅质碎屑碳酸盐成分，整个断面不含碳酸盐。Tas-Ary和Bel'kov地层之间的边界对应于陆架到盆地剖面和沉积样式的变化。这时（Serpukhovian的开始），沉降速率增加，形成了明显的斜坡，并且陆上出现了新的碎屑来源。这种重组可能与北泰米尔造山带上升有关。塔斯-阿里半岛和泰米尔南部石炭纪下层的岩性相似，沉积从碳酸盐岩到陆源岩的同步转变以及两个地区上石炭统-二叠纪砂岩的碎屑物质来源相同，表明它们属于晚古生代的同一沉积盆地。我们认为，新西伯利亚群岛的西部是泥盆纪晚期的大陆边缘，石炭纪和二叠纪，这是Verkhoyansk边缘的延续。考虑到新西伯利亚群岛地块的旋转，根据美亚盆地开口的两极旋转模型，后者是可能的。